Strange Tru-Oil Problem

[ejko]

For the first time in ages, the temperature dipped under the nineties, so I decided to play a while on the screened porch. I had to go in for about 20 minutes, and I left the guitar on the porch (apparently in direct sunlight). When I came back, there were 20-30 1/8” to 1/4” bubbles on the Sitka top. The guitar was finished with Tru-Oil ten years ago, and until today looked great. I’m assuming the Tru-Oil bubbled up from the sunlight, which seems pretty amazing after 10 years. I’m thinking I may need to buy some Tru-Oil to go over the top with and hopefully the solvent on it will break down the bubbles. Thoughts and suggestions are appreciated.

[Glen H]

Leave it be for a while. Maybe they’ll go back down?

[Fathand]

There is some discussion here about Tru Oil bubbling in the sun while drying too fast. Not sure it's the same problem but the suggestion is to sand or scotchbrite it off. In my limited experience, Ive found that stripping and starting over is usually the faster choice for major finish problems.

https://www.mylespaul.com/threads/do....441148/page-2

[runamuck]

Originally Posted by ejko

For the first time in ages, the temperature dipped under the nineties, so I decided to play a while on the screened porch. I had to go in for about 20 minutes, and I left the guitar on the porch (apparently in direct sunlight). When I came back, there were 20-30 1/8” to 1/4” bubbles on the Sitka top. The guitar was finished with Tru-Oil ten years ago, and until today looked great. I’m assuming the Tru-Oil bubbled up from the sunlight, which seems pretty amazing after 10 years. I’m thinking I may need to buy some Tru-Oil to go over the top with and hopefully the solvent on it will break down the bubbles. Thoughts and suggestions are appreciated.

Wow! I have never experienced nor read of that happening with any finish. I've never used Tru Oil but have used several similar finishes and this a surprise to me.

I doubt that it'll just lay back down and I also doubt that applying a new coat will emulsify a cured finish.

[difalkner]

Hate that happened but I'm a bit surprised. Tru-Oil is used on gun stocks and holds up amazingly well in all sorts of environments. About 40 years ago for my first trip to Yosemite I made a couple of walking sticks out of Red Oak and finished them with Tru-Oil; they still look great even though I've beat them against trees and rocks a thousand times.

[ejko]

Yes, it is very strange to me too. Looking back, I built this guitar in 2006. It has looked great all that time. I'm just amazed that after 17 years the finish would react like this. One would think it would have been bone dry for over a decade at least.

I may try diluting a new batch of Tru-Oil with mineral spirits then wiping it on to see of I can get the 'bubbles' back in solution. I really hate to sand or scotchbrite it down, since over the years it has a great aged glow to it.

Life's surprises never end!

[printer2]

Originally Posted by difalkner

Hate that happened but I'm a bit surprised. Tru-Oil is used on gun stocks and holds up amazingly well in all sorts of environments. About 40 years ago for my first trip to Yosemite I made a couple of walking sticks out of Red Oak and finished them with Tru-Oil; they still look great even though I've beat them against trees and rocks a thousand times.

I guess the trees and rocks never di answer you?

[redir]

Originally Posted by difalkner

Hate that happened but I'm a bit surprised. Tru-Oil is used on gun stocks and holds up amazingly well in all sorts of environments. About 40 years ago for my first trip to Yosemite I made a couple of walking sticks out of Red Oak and finished them with Tru-Oil; they still look great even though I've beat them against trees and rocks a thousand times.

I wonder if maybe the guitar had some sort of sealant like shellac before adding the Tru-Oil? I agree it's odd being a well known gun stock finish and hunters take their guns through all sorts of conditions.

[Fawkes]

Originally Posted by ejko

I may try diluting a new batch of Tru-Oil with mineral spirits then wiping it on to see of I can get the 'bubbles' back in solution. I really hate to sand or scotchbrite it down, since over the years it has a great aged glow to it.

I would be surprised if cured Tru-oil could be 'reconstituted' or dissolved in this way. I would expect it to act more like a varnish, meaning that depending on its age it will need a more or less strong solvent to dissolve, but won't return to its original cohesive state once that solvent dries.

If the various plucked string forums with repair sections don't come up with an answer, you might want to check with violin repair people, they have run into just about everything.

Hopefully you run into some crazy drop-fill stunt that does the trick with minimal fuss.

[Howard Klepper]

You baked it. A lot of finishes will bubble when exposed to enough heat.

No thinner/vehicle/reducer for the liquid finish is going to be a solvent for the cured finish, which is polymerized linseed oil. You either live with it, or refinish it. Also check the top for loose braces.

[ejko]

You all were right. No solvent I tried touched it, so out came the sandpaper. Tru-Oil is pretty tough to sand down. Just put on the first coat. Likely several more coats to come. Thanks to all for you insights and help.